Watch: colors and a second page
In the full walkthrough, the early section sets body and background colors, then adds another page.
Early in NHDWebCentral Walkthrough, the page is blank. The middle area is the body, where the content goes. The area outside that is the background. The video changes those colors from the toolbar.
It then adds another page, using a thesis page as the example, with a title and a navigation bar, and saves.
Shorter written steps are in The three parts of the builder, Add and name a page, and Create your own color theme.